Changes in the neuroanatomical and neurophysiological organization of the dorsal lateral geniculate nucleus (dLGN) and visual cortex of Macaca monkeys will be studied during development in normal and monocularly deprived animals. The neurons and synapses utilizing GABA, acetylcholine, catecholamines and indoleamines as transmitters will be identified in dLGN and visual cortex by means of EM autoradiography and fluorescence histochemistry. The effect of monocular deprivation on the distribution and amount of these transmitters will be assessed to test the hypothesis that deprivation is caused by excessive inhibition at one or both of these levels. The contrast sensitivity function of normal, monocularly deprived and deprivation-reversed monkeys will be determined by behavioral testing and neurophysiological recording in optic tract, dLGN and visual cortex to further delineate the channels within the visual system that are affected by deprivation.